Manual Pages for UNIX Operating System command usage for man pthread_mutexattr_setrobust

Standard C Library Functions      pthread_mutexattr_getrobust(3C)



NAME
     pthread_mutexattr_getrobust,  pthread_mutexattr_setrobust  -
     get and set the mutex robust attribute

SYNOPSIS
     cc -mt [ flag... ] file... [ library... ]
     #include 

     int pthread_mutexattr_getrobust(const pthread_mutexattr_t *attr,
          int *robust);


     int pthread_mutexattr_setrobust(pthread_mutexattr_t *attr,
          int robust);


DESCRIPTION
     The            pthread_mutexattr_getrobust()             and
     pthread_mutexattr_setrobust()  functions, respectively,  get
     and set the mutex robust attribute. This attribute is set in
     the robust parameter. Valid values for robust include:

     PTHREAD_MUTEX_STALLED

         No special actions are taken if the owner of  the  mutex
         is  terminated  while  holding  the mutex lock. This can
         lead to deadlocks because no other thread can unlock the
         mutex. This is the default value.


     PTHREAD_MUTEX_ROBUST

         If the owning thread of a robust mutex terminates  while
         holding the mutex lock, or if the process containing the
         owning thread of a robust mutex terminates, either  nor-
         mally  or  abnormally,  or if the process containing the
         owner of the mutex  unmaps  the  memory  containing  the
         mutex or performs one of the exec(2) functions, the next
         thread that acquires the mutex will be notified  by  the
         return value EOWNERDEAD from the locking function.

         The notified thread can  then  attempt  to  recover  the
         state  protected  by  the mutex and, if successful, mark
         the  state  as   consistent   again   by   a   call   to
         pthread_mutex_consistent().  After a subsequent success-
         ful call to  pthread_mutex_unlock(3C),  the  mutex  lock
         will  be  released  and  can  be  used normally by other
         threads.  If the mutex is unlocked  without  a  call  to
         pthread_mutex_consistent(),  it will be in a permanently
         unusable state and all attempts to lock the  mutex  will
         fail with the error ENOTRECOVERABLE.  The only permissi-
         ble     operation     on     such     a     mutex     is



SunOS 5.11          Last change: 11 Nov 2008                    1






Standard C Library Functions      pthread_mutexattr_getrobust(3C)



         pthread_mutex_destroy(3C).

         The actions required to make the state protected by  the
         mutex  consistent  are  solely dependent on the applica-
         tion.  Calling pthread_mutex_consistent(3C) does not, by
         itself,  make  the  state  protected  by  the mutex con-
         sistent.

         The behavior is undefined if the value specified by  the
         attr   argument   to   pthread_mutexattr_getrobust()  or
         pthread_mutexattr_setrobust() does not refer to an  ini-
         tialized mutex attributes object.


RETURN VALUES
     Upon          successful           completion,           the
     pthread_mutexattr_getrobust()  function returns 0 and stores
     the value of the robust attribute of attr  into  the  object
     referenced  by  the  robust  parameter.  Otherwise, an error
     value is returned to indicate the error.


     Upon          successful           completion,           the
     pthread_mutexattr_setrobust() function returns 0. Otherwise,
     an error value is returned to indicate the error.

ERRORS
     The pthread_mutexattr_setrobust() function will fail if:

     EINVAL    The value of robust is invalid.


ATTRIBUTES
     See attributes(5)  for descriptions of the following  attri-
     butes:




















SunOS 5.11          Last change: 11 Nov 2008                    2






Standard C Library Functions      pthread_mutexattr_getrobust(3C)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    |  MT-Safe                    |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


SEE ALSO
     exec(2),                       pthread_mutex_consistent(3C),
     pthread_mutex_destroy(3C),           pthread_mutex_init(3C),
     pthread_mutex_lock(3C),            pthread_mutex_unlock(3C),
     pthread_mutexattr_getpshared(3C),
     pthread_mutexattr_init(3C), attributes(5),  mutex(5),  stan-
     dards(5)

NOTES
     The mutex memory must be zeroed before first  initialization
     of  a  mutex  with  the  PTHREAD_MUTEX_ROBUST attribute. Any
     thread in any process interested in the robust lock can call
     pthread_mutex_init()  to potentially initialize it, provided
     that all such callers of  pthread_mutex_init()  specify  the
     same  set  of  attributes  in their attribute structures. In
     this situation, if pthread_mutex_init() is called on a  pre-
     viously  initialized  robust mutex, it will not reinitialize
     the  mutex  and  will  return  the  error  value  EBUSY.  If
     pthread_mutex_init()  is  called on a previously initialized
     robust mutex, and if the caller specifies a different set of
     attributes  from  those  already in effect for the mutex, it
     will not reinitialize the mutex and will  return  the  error
     value EINVAL.





















SunOS 5.11          Last change: 11 Nov 2008                    3